As a make-up artist I know and understand the value of a persons undertone. Each time I'm working with a model or a celeb I always bare in mind their undertone. The undertone of a person can be "Cool or Warm". When it comes to make-up it is very important to know your undertone. For example the wrong lipstick tone could make you look washed-out or muddy. I can never express enough the value of keeping your undertone in mind whenever you a buying make-up.